We're opening soon. Tell me when

Yard & Field

Buying guides

Looking after a wooden shed: treatment, felt and yearly checks

By the Yard & Field team

Updated

Rot needs water. A wooden shed lasts when the timber is kept treated, the roof keeps the rain out, and the building stays off wet ground with air moving round it.

Does my shed need treating every year?

Dip-treated timber has a preservative coat on the surface. Makers ask for it to be re-treated every year, and the guarantee against rot usually only stands if you do. Some say the treatment applied at the factory is only there to protect the timber in transit, so the first coat goes on as soon as the shed is built.

Pressure-treated timber has preservative forced into the wood under pressure, so it resists rot without a yearly preserver. Some makers' guarantees still ask for a yearly waterproofing coat though, so check yours. Any cut ends still need sealing with a preserver, and a coloured finish is up to you. Protek, the timber stain maker, says fresh pressure-treated timber should weather for up to a year before it's stained, or be washed first. Other makers differ, so follow the tin.

Advice on how often differs. Shed makers say every year. Some retailers say every one to two years, depending on the weather where you are. Coloured shed treatments claim colour and weather protection for up to five or six years. Those claims are about the finish, not rot, and one leading colour range asks for bare wood to be treated with a wood preserver first. For a dip-treated shed, follow the maker's yearly rule.

Preserver, stain or paint?

Some shed makers also recommend a coat of preserver on the inside, so the timber doesn't soak up moisture from within.

When should I do it?

How do I re-treat a shed?

  1. Repair first. Replace any soft or rotten sections and fill small holes with exterior wood filler.
  2. Brush off dirt, cobwebs and flaking finish. Scrub off algae, moss or lichen with an outdoor or fungicidal cleaner, rinse and let it dry.
  3. Cover plants and paths, and mask handles, hinges and glass. Keep treatment out of ponds and drains: some preservers are harmful to aquatic life.
  4. Brush along the grain in even coats, working it in rather than spreading it thin. Dab the end grain at corners and board ends so it soaks in.
  5. Most treatments want two coats. Wax-enriched ones repel water, so the second coat goes on within two or three days of the first. The tin gives the drying and recoat times.

Keep children and pets away until it's fully dry. For a hen house or hutch, use a product its maker says is suitable for animal housing, and let it dry before the animals go back in.

How long does roof felt last?

Shed makers put standard green mineral felt at around five years. Power Sheds says polyester-backed felt is much harder to tear and can last up to 15 years, and gives an EPDM rubber roof a life expectancy of 50 years.

How do I know the felt needs replacing?

Rather than patch a damaged roof, it's better to strip the old felt, replace any rotten boards and re-felt it. Sand-backed felt is a base layer and shouldn't be used on its own.

Work from a stable stepladder with someone to steady it, and never climb onto the roof itself.

How do I keep water away from the shed?

Why does my shed get condensation?

Damp air inside a closed shed condenses on the walls, roof and tools, and wood that stays damp is far more likely to rot. Moving air is the fix:

A yearly checklist

Please note: this guide is general advice to help you choose, not professional or legal advice. Every garden and every product is different, so always follow the maker's instructions and check with your council or a qualified tradesperson if you're unsure.

Sources

See also: choosing a garden shed and shed bases.